# def is_prime(n):
#     if n<2:
#         return False
#     for i in range(2,int(n**0.5)+1):
#         if n%i==0:
#             return False
#     return True
# print(is_prime(30))
# def test(*args):
#     print(args)
# test(1,2,3,4,5,6,7)
def f(n):
    if n==1:
        return 1
    else:
        return n* (n-1)
# 测试用例

